As is known to those skilled in the art, a subway is an underground urban railroad which usually is operated by electricity. See, e.g., U.S. Pat. Nos. 5,108,171, 4,854,078, 4,573,559, 4,233,904, 4,081,083, 4,008,577, 3,999,394, 3,914,946, 3,851,881, and 3,704,064. The disclosure of each of these patents is hereby incorporated by reference into this specification.
The electrical power required to move subway trains is usually transmitted by means of a "third rail" which runs parallel to one of the rails of the subway track. See, e.g., FIG. 2 of page 346 of the McGraw-Hill Encyclopedia of Science & Technology, Volume 11 (McGraw-Hill Book Company, New York, 1977).
It is often necessary to park a subway train on the rails of a subway track when such train is not in use and/or is being serviced and to restrain the movement of such a train.
It is an object of this invention to provide a wheel chock which can be readily wedged between the wheel of a subway train and a track and can readily and effectively prevent the movement of such wheel and such train.
It is another object of this invention to provide a wheel chock which is electrically non-conductive and, thus, will not conduct electricity from the third rail of a subway system to any portion of a subway car.
It is yet another object of this invention to provide a wheel chock which is comprised of means for readily wedging it between a wheel and a track.
It is yet another object of this invention to provide a wheel chock comprised of means for preventing the sliding movement of such wheel chock on a subway track.
It is yet another object of this invention to provide a wheel chock which may be wedged between a wheel and a rail from either side of the railroad car.